Background: A Phase II study of combination treatment with 5-fluorouracil (5-FU), leucovorin (LV), and interferon alpha-2a (IFN) in patients with previously untreated metastatic colorectal cancer was previously reported by the authors. Therapy was on an outpatient basis and consisted of LV 60 mg orally every 8 hours days 1-3, IFN 18 x 10(6) IU subcutaneously days 1-3, and bolus 5-FU 750 mg/m2 intravenously days 2-3. Treatment was repeated every 14 days, until a maximum of 8 courses was administered. A response rate of 54% [95% confidence interval (CI), 34-72%] was observed. However, remission duration after cessation of therapy was short, with a median duration of 5 months (range, 2 to 13+ months).
Methods: Subsequent to the above study, patients on this induction treatment who achieved remission received maintenance therapy: the above described 3-day regimen every 6 weeks until progression, for a maximum of 2 years.
Results: Fifty-three patients were enrolled in the induction regimen and 18 out of 29 patients who achieved remission received maintenance treatment. In 50 assessable patients 3 complete recoveries and 26 partial recoveries were observed for a response rate of 58% (CI, 43-72%). Median remission duration of patients receiving maintenance therapy was 9.4 months (CI, 8.4-10.3 months) compared with 4.7 months (CI, 3.2-6.2 months) for patients without maintenance therapy. Median overall survival of all patients was 16.6 months. Toxicity of maintenance therapy was confined to WHO grade 2.
Conclusions: The high response rate of this 5-FU/LV/IFN regimen holds true in a larger group of patients. The group that received maintenance treatment had a remission duration of just over 9 months, the maintenance regimen added little toxicity.